In carrying out industrial processes that involve hazardous or combustible substances, there is always a risk that a malfunction may result in damage or injury. To minimize the damage caused by such a malfunction, it is desirable to shut off the flow of hazardous substances as soon as the emergency is detected. This is particularly true in industrial operations that employ combustible fuels such as natural gas for heating in a furnace or oven. In the event of a malfunction which causes a fire in the area of the furnace or oven, it is desirable to shut off the flow of combustible gas as soon as the fire condition is sensed.
Industrial furnaces and ovens are often equipped with automatic fire detection and extinguishing systems. Such systems are designed to sense a fire or an overheated condition and to spray CO2, dry chemical, foam or another type of fire extinguishing agent on the fire. When the fire extinguishing system is triggered, it is almost always desirable to shut off the flow of fuel to the furnace or oven. Of course, when the emergency condition is corrected, it is necessary to reinstitute the flow of gas so that the process may be restarted.
Various types of systems have been devised which use conventional valves to shut off the flow of combustible material to a furnace or oven when a fire occurs. Such systems involve components such as sensors, relays, solenoids, transformers and other items which may malfunction. A malfunction could result in the fuel continuing to be delivered even after the fire extinguishing system is tripped. This may defeat the fire extinguishing system.
Thus, there exists a need for a device which will shut off the flow of combustible fuel to an industrial furnace or oven or other type of heating device when a fire extinguishing system is tripped. There further exists a need for a device that is less costly and has greater reliability than prior devices and systems.